Motor vehicles typically comprise a number of electrical systems configured to implement critical and non-critical vehicle functions. Electrical systems include the powertrain system (controlled by a powertrain control module, PCM), safety system (controlled by a safety system control module, SCM) and body electrical system (controlled by a body control module, BCM). The modules may communicate with one another by means of a common area network, for example a Controller Area Network (CAN) bus or the like.
Due to package constraints and to aid installation wires associated with vehicle electrical systems may be arranged to follow common paths within a vehicle to connect different components, such as controllers, actuators, switch packs and lighting modules. A relatively large number of cables or wires may follow any given path. The cables are typically bound together forming a cable or wiring assembly or harness. The assembly may also be referred to as a cable or wiring loom. Binding of the cables together has the advantage that it reduces a flexibility of the cables. This may reduce a risk of damage to a cable and aid installation of the cables.
During vehicle development it is known to provide a test station at which a vehicle harness is constructed on a test bench. The harness is connected to actual components that will be connected to the harness in the vehicle, or to modules that simulate such components. Cables making up the harness may be of reduced length compared with actual cables to be used in the vehicle due to a reduced size of the test bench component layout.
The harness is connected to a test station controller. The controller may monitor signals transmitted by one or more cables of the harness such as a network cable carrying network signals such as CAN bus signals. The controller may also transmit CAN bus signals onto the network cable. The controller may be operable to simulate signals transmitted by any absent control modules or signals transmitted by a control module under certain conditions that cannot otherwise be reproduced at the test station, such as signals transmitted by the powertrain control module when an engine is running.
Some known controllers are operable to run software code arranged to command prescribed control operations to be performed by control modules connected to the CAN bus, and to monitor a response of the control modules by monitoring signals transmitted by the modules on the CAN bus. A portion of software code performing a given sequence of control operations may be referred to as a script.
It is an aim of embodiments of the invention to provide improved apparatus for monitoring motor vehicle electrical systems.